Atherosclerosis is a frequent cause of vascular diseases in the United States. Contrast angiography has been the gold standard for the diagnosis and management of these diseases. Because of the difficult handling and reprocessing of film images data, there have been few techniques developed for quantitative hemodynamic measurement or image synthesis. Recent introduction of digital subtraction angiography (DS) has enabled various image subtraction schemes to be incorporated and used to optimize the visualization of marginally opacified vessels. It also facilitates the development and implementation of videodensitometric techniques for quantitative hemodynamic measurement. However, intrinsic to the use of the image intensifier as the x-ray detector in DSA is the acceptance of scattered radiation and veiling giare as an additional component in the image signal. This component results in erroenous x-ray transmission measurement, leading to inaccuracies in videodensitometric studies as well as energy subtraction imaging. In this research work, we propose to develop and study several new techniques to correct DSA images data for more accurate x-ray transmission measurement. The techniques involve the use of scanning lead bar patterns for the measurement and removal of scattered radiation and veiling glare component or scanning iodine phantoms for direct measurement of iodine sensitivity. They will be incorporated with DSA imaging procedures for videodensitometric studies and dual energy subtraction imaging. Phantom experiments and animal studies will be conducted to evaluate the proposed image correction techniques for their effectiveness in the improvement of accuracy in these applications.